According to U.S. Pat. No. 4,609,574 (published 2 September 1986, J R. Keryk et al., Dow Corning Corporation), organopolysiloxane compositions containing Si-bonded higher alkenyl groups, such as, for example 5-hexenyl groups, are more reactive than Si-bonded vinyl groups toward Si-bonded hydrogen. The organopolysiloxanes containing higher alkenyl groups can be prepared by reacting an organopolysiloxane containing Si-bonded hydrogen with an .alpha., w-diene; however, multiple addition reactions always occur. The organopolysiloxanes containing higher alkenyl groups are therefore preferably obtained from the corresponding silanes by reacting an .alpha., w-diene in a large excess with a silane containing Si-bonded hydrogen and subsequently hydrolyzing the silane and equilibrating the silane with an organopolysiloxane.
E. Lukevits et al., Zhurnal Obshchei Khimii, Vol. 56, 140-143, 1986 (Chemical Abstracts, Vol. 105, 226720 h, 1986) describe the hydrosilylation of alkenes and alkynes using dimethyl(2-thienyl)silane. The triple bond is more reactive than the double bond.
In M. G. Voronkov, Irk, Inst. Org. Khim., 55(9), 2091-3 (Chemical Abstracts, Vol. 105, 97545d, 1986), the reaction of 1-allyloxy-3-propargyloxy-2-propanol with trialkylsilanes is described, in which yields of up to 70% have been achieved.
In M. Licchelli, A. Greco, Tetrahedron Lett. 28 (1987) 3719-22 the hydrosilylation of 2-methyl-1-buten-3-yne using methylchlorosilanes is described, in which the hydrosilylation of the conjugated alkenyne results in both the mono- and di-addition of the silanes.
In M. G. Veliev, Azerb, Khim, Zh. 1987 (1) 60-4 (Chemical Abstracts, Vol. 110, 135304n), the reaction of a silane with an organic compound which has both a carbon-carbon double bond and a triple bond is described, in which the organic compound contains an epoxy or a cyano group.
The German application P 3935775.9 (application date 27 October 1989, Wacker-Chemie GmbH) and the corresponding US application 1990) now U.S. Pat No. 5,113,006 disclose that organosilicon compounds containing alkenyl groups in which the individual carbon-carbon double bonds within a molecular moiety are relatively close to each other, have an inhibiting effect in a reaction with Si-bonded hydrogen.
Therefore, it is an object of the present invention to provide a process for selectively preparing organosilicon compounds containing alkenyl groups. A further object of the present invention is to provide organosilicon compounds containing alkenyl groups which are prepared by a simple process.